generate ts declaration from lang file

// eslint-disable-next-line @typescript-eslint/no-var-requires
const fs = require('fs');
// eslint-disable-next-line @typescript-eslint/no-var-requires
const path = require('path');
// eslint-disable-next-line @typescript-eslint/no-var-requires
const en = require('../resources/en.json');

function generateFromLangObj(lng, prefix = '') {
    return Object.keys(lng)
        .reduce((acc, key) => {
            const i18nKey = (prefix ? prefix + '.' : '') + key;
            if (typeof lng[key] === 'object') {
                return acc.concat(generateFromLangObj(lng[key], i18nKey));
            }
            return acc.concat([`'${i18nKey}'`]);
        }, [])
        .join('|');
}

function generateEnDeclarations() {
    return 'export type i18nKey = ' + generateFromLangObj(en.translations) + `|''`;
}

const enDeclarationsPath = path.resolve(__dirname, '../en.ts');
fs.writeFileSync(enDeclarationsPath, generateEnDeclarations());
fs.watchFile(enDeclarationsPath, generateEnDeclarations);